Problem: Find the output, $g$, when the input, $r$, is $4$. $g= 25-3r$ $g=$
To find the output, ${g}$, we need to substitute ${4}$ into the equation for ${r}$. $\begin{aligned} {g}&=25-3{r}\\\\ {g}&=25-3\cdot{4}\\\\ &=25-12\\\\ &={13} \end{aligned}$ When the input is $4$, the output is $13$.